U.S. patent application number 15/208334 was filed with the patent office on 2017-05-11 for composite abrasive particles for chemical mechanical planarization composition and method of use thereof.
This patent application is currently assigned to Air Products and Chemicals, Inc.. The applicant listed for this patent is Air Products and Chemicals, Inc.. Invention is credited to Krishna P. Murella, Dnyanesh Chandrakant Tamboli, Hongjun Zhou.
Application Number | 20170133236 15/208334 |
Document ID | / |
Family ID | 56367079 |
Filed Date | 2017-05-11 |
United States Patent
Application |
20170133236 |
Kind Code |
A1 |
Murella; Krishna P. ; et
al. |
May 11, 2017 |
Composite Abrasive Particles For Chemical Mechanical Planarization
Composition And Method Of Use Thereof
Abstract
Polishing compositions comprising ceria coated silica particles
offer minimal topography, reduced oxide and nitride losses, while
providing high oxide polish rates. These formulations are
especially useful for polishing large structures typically used in
3D NAND device manufacturing.
Inventors: |
Murella; Krishna P.;
(Phoenix, AZ) ; Zhou; Hongjun; (Chandler, AZ)
; Tamboli; Dnyanesh Chandrakant; (Gilbert, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Air Products and Chemicals, Inc. |
Allentown |
PA |
US |
|
|
Assignee: |
Air Products and Chemicals,
Inc.
Allentown
PA
|
Family ID: |
56367079 |
Appl. No.: |
15/208334 |
Filed: |
July 12, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14993128 |
Jan 12, 2016 |
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15208334 |
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PCT/US2016/012993 |
Jan 12, 2016 |
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14993128 |
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62221379 |
Sep 21, 2015 |
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62286606 |
Jan 25, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C09K 3/1436 20130101;
H01L 21/31053 20130101; H01L 21/30625 20130101; C09G 1/02 20130101;
B24B 37/24 20130101; C09K 3/1445 20130101 |
International
Class: |
H01L 21/306 20060101
H01L021/306; C09K 3/14 20060101 C09K003/14; C09G 1/02 20060101
C09G001/02 |
Claims
1. A polishing composition comprising: composite particles
comprising core particles with surfaces covered by nanoparticles;
one or more additives selected from polymeric carboxylic acids and
salts thereof and one or more additives selected from polymers
containing alkoxylate groups; a pH-adjusting agent selected from
the group consisting of sodium hydroxide, potassium hydroxide,
cesium hydroxide, ammonium hydroxide, quaternary organic ammonium
hydroxide, and combinations thereof; and DI water; wherein the core
particle is selected from the group consisting of silica, alumina,
titania, zirconia, polymer particle, and combinations thereof; and
the nanoparticle is selected from the compounds of a group
consisting of zirconium, titanium, iron, manganese, zinc, cerium,
yttrium, calcium, magnesium, fluorine, lanthanum, strontium
nanoparticle, and combinations thereof; and the polishing
composition has a pH of about 2 to about 12.
2. The polishing composition of claim 1 wherein the core particle
is silica particle, the nanoparticle is ceria nanoparticle, wherein
the silica is amorphous silica and the ceria nanoparticles are
singly crystalline.
3. The polishing composition of claim 1, wherein said polymeric
carboxylic acids and salts thereof are selected from the group
consisting of polyacrylic acid, poly-methacrylic acid, poly(methyl
methacrylate) (PMMA), polyvinyl alcohol and polystyrenesulfonic
acid or salts thereof.
4. The polishing composition of claim 1 wherein said polymers
having alkoxylate groups are selected from the group consisting of
polyethylene glycol and polyethylene oxide.
5. The polishing composition of claim 1 wherein said polymeric
carboxylic acids and salts thereof is ammonium polyacrylate and
wherein said polyols having hydroxyl groups is polyethylene
glycol.
6. The polishing composition of claim 1 having a pH ranging from 4
to 10.
7. The polishing composition of claim 6 comprising ceria coated
silica composite particles, and ammonium hydroxide; and having a pH
ranging from 4 to 8.
8. A polishing method for chemical mechanical planarization of a
semiconductor substrate comprising at least one surface having at
least one oxide layer and at least one stopping layer beneath at
least part of said at least one oxide layer, and at least one
trench within said substrate, said at least one trench comprising a
portion of said at least one oxide layer in said trench, said at
least one trench having a trench width of greater than 0.01 mm,
said at least one oxide layer comprises one or more active oxide
regions located on either side of said at least one trench, said
one or more active oxide regions having a width greater than 0.1
mm, comprising the steps of: a) contacting the at least one active
oxide regions with a polishing pad; b) delivering a polishing
composition to the at least one surface, the polishing composition
comprising: composite particles comprising core particles with
surfaces covered by nanoparticles; an additive selected from a
compound having a functional group selected from the group
consisting of organic carboxylic acids, amino acids,
amidocarboxylic acids, N-acylamino acids, and their salts thereof;
organic sulfonic acids and salts thereof; organic phosphonic acids
and salts thereof; polymeric carboxylic acids and salts thereof;
polymeric sulfonic acids and salts thereof; polymeric phosphonic
acids and salts thereof; arylamines, aminoalcohols, aliphatic
amines, heterocyclic amines, hydroxamic acids, substituted phenols,
sulfonamides, thiols, polyols having hydroxyl groups, polymers with
alkoxylate groups and combinations thereof; a pH-adjusting agent
selected from the group consisting of sodium hydroxide, potassium
hydroxide, cesium hydroxide, ammonium hydroxide, quaternary organic
ammonium hydroxide, and combinations thereof; and DI water; wherein
the core particle is selected from the group consisting of silica,
alumina, titania, zirconia, polymer particle, and combinations
thereof; and the nanoparticle is selected from the compounds of a
group consisting of zirconium, titanium, iron, manganese, zinc,
cerium, yttrium, calcium, magnesium, fluorine, lanthanum, strontium
nanoparticle, and combinations thereof; and the polishing
composition has a pH of about 2 to about 12; and C) polishing the
at least one active oxide region with the polishing composition to
expose said stopping layer.
9. The method of claim 8, wherein the nanoparticle is ceria
nanoparticle, and the composite particles are amorphous silica
particles having surfaces covered by singly crystalline ceria
nanoparticles.
10. The method of claim 9, wherein the polishing composition has a
pH ranging from 4 to 10.
11. The method of claim 8, wherein the polishing composition
further comprises one or more additives selected from polymeric
carboxylic acids and salts thereof and one or more additives
selected from the group consisting of polymers containing alkoylate
groups.
12. The method of claim 11, wherein the polishing composition
comprises ceria coated silica composite particles, ammonium
hydroxide; and has a pH ranging from 4 to 8.
14. The method of claim 11, wherein said one or more additives
selected from polymeric carboxylic acids and salts thereof are
selected from the group consisting of polyacrylic acid,
poly-methacrylic acid, polyvinyl alcohol and polystyrenesulfonic
acid or salts thereof, and said one or more additives selected from
the group consisting of polymers with alkoxylate groups are
selected from the group consisting of polyethylene glycol and
polyethylene oxide.
15. The method of claim 8, wherein the at least one oxide layer is
a silicon oxide layer.
16. The method of claim 15, wherein polishing removal rate for the
at least one oxide layer is equal to or greater than 5000
.ANG./min.
17. The method of claim 8 wherein at least one trench has a trench
width of 0.01 mm to 10 mm and at least a one of the one or more
active oxide regions has a width ranging from 0.1 mm to 50 mm.
18. The method of claim 8 wherein said substrate has at least two
trenches, and at least two active oxide regions, each of said at
least two trenches having a trench width of 0.01 mm to 10 mm and
each of said at least two active oxide regions, having a width
ranging from 0.1 mm to 50 mm
19. The method of claim 8 wherein at least one of the one or more
active oxide regions is greater than 1 micron in height prior to
said polishing step.
20. The method of claim 8 wherein the structure is used for 3D-NAND
memory fabrication.
21. A system for chemical mechanical planarization, comprising: a
semiconductor substrate comprising at least one surface having at
least one oxide layer and at least one trench having a width of at
least 0.01 mm; a polishing pad; and a polishing composition
comprising: composite particles comprising core particles with
surfaces covered by nanoparticles; an additive selected from a
compound having a functional group selected from the group
consisting of organic carboxylic acids, amino acids,
amidocarboxylic acids, N-acylamino acids, and their salts thereof;
organic sulfonic acids and salts thereof; organic phosphonic acids
and salts thereof; polymeric carboxylic acids and salts thereof;
polymeric sulfonic acids and salts thereof; polymeric phosphonic
acids and salts thereof; arylamines, aminoalcohols, aliphatic
amines, heterocyclic amines, hydroxamic acids, substituted phenols,
sulfonamides, thiols, polyols having hydroxyl groups, polymers with
alkoxylate groups and combinations thereof; a pH-adjusting agent
selected from the group consisting of sodium hydroxide, potassium
hydroxide, cesium hydroxide, ammonium hydroxide, quaternary organic
ammonium hydroxide, and combinations thereof; and DI water; wherein
the core particle is selected from the group consisting of silica,
alumina, titania, zirconia, polymer particle, and combinations
thereof; and the nanoparticle is selected from the compounds of a
group consisting of zirconium, titanium, iron, manganese, zinc,
cerium, yttrium, calcium, magnesium, fluorine, lanthanum, strontium
nanoparticle, and combinations thereof; and the polishing
composition has a pH of about 2 to about 12; and wherein the at
least one oxide layer is in contact with the polishing pad and the
polishing composition.
22. The system of claim 21, wherein the nanoparticle is ceria
nanoparticle, and the composite particles are amorphous silica
particles having surfaces covered by singly crystalline ceria
nanoparticles.
23. The system of claim 21, wherein the polishing composition has a
pH ranging from 4 to 10 and the change of size distribution of
composite particles under a disintegrative force is less than
5%;
24. The system of claim 21, wherein the polishing composition
further comprises one or more additives selected from polymeric
carboxylic acids and salts thereof selected from the group
consisting of polyacrylic acid, poly-methacrylic acid, polyvinyl
alcohol and polystyrenesulfonic acid or salts thereof, and one or
more additives selected from the group consisting of polymers with
alkoxylate groups selected from the group consisting of
polyethylene glycol and polyethylene oxide.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. provisional
applications 62/221,379 filed on Sep. 21, 2015, U.S. application
Ser. No. 14/993128 filed on Jan. 12, 2016 and PCT Application U.S.
Ser. No. 16/12993 filed on Jan. 12, 2016, US provisional
application 62/286606 filed Jan. 25, 2016, the entire contents of
all are incorporated herein by reference thereto for all allowable
purposes.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to chemical mechanical
planarization ("CMP") polishing compositions (CMP slurries, CMP
composition or CMP formulations are used interchangeably) used in
the production of a semiconductor device, and polishing methods for
carrying out chemical mechanical planarization. In particular, it
relates to polishing compositions comprising composite abrasive
particles that are suitably used for polishing patterned
semiconductor wafers that composed of oxide materials.
[0003] Silicon oxide is widely used as dielectric materials in
semiconductor industry. There are several CMP steps in integrated
circuit (IC) manufacturing process, such as shallow trench
isolation (STI), inter-layer dielectric (ILD) CMP and gate poly CMP
etc. Typical oxide CMP slurry involves: abrasive, with or without
other chemicals. Other chemicals could be dispersants to improve
slurry stability, booster to increase removal rate, or inhibitors
to decrease removal rate and to stop on the other film, for
example, SiN for STI application.
[0004] Among common abrasives used in CMP slurries, such as silica,
alumina, zirconia, titania and so on, ceria is well-known for its
high reactivity toward silica oxide and is widely used in STI CMP
slurry for the highest oxide removal rate (RR) due to the high
reactivity of ceria to silica.
[0005] Cook et al. (Lee M. Cook, Journal of Non-Crystalline Solids
120 (1990) 152-171) proposed a `chemical tooth` mechanism to
explain this extraordinary property of ceria. According to this
mechanism, when ceria particles are pressed onto silicon oxide
film, ceria breaks down silica bonds, forms a Ce--O--Si structure
and thus cleavage silica from the surface.
[0006] As the semiconductor technology has evolved, there are a
number of new applications that demand innovative CMP solutions to
meet requirements of high silicon oxide removal rates and a high
degree of planarity. One of such applications is in manufacturing
three-dimensional (3D) memory structures. 3D memory structures
stacks the memory cells vertically allowing a wider gap between
each cell, overcoming the patterning restrictions. 3D NAND
typically uses alternating layers of thick (height) oxides and
nitride or oxide and conductor layers to form vertical NAND
structures in the form of a staircase. Oxide layers are typically
thicker (have a height greater) than 1 micron or 2 microns or 3
microns. In order to maintain throughput requirements, oxide layers
need to be polished at very high rates, stop on the optional second
film or stopping layer (located beneath the oxide layer) such as
nitride or poly-Si layer and cause minimal dishing of the oxide
trench structures. Many of the high rate oxide CMP slurries
available in the market cause a dome-like topography during
polishing. The dome or rounded features are formed of residual
oxide in the oxide regions (active oxide regions) surrounding the
trenches while polishing thick and wide oxide structures. It is
important to minimize rounding of large oxide structures (thereby
forming the dome-like topography) to minimize oxide loss in
trenches and prevent complete loss of stopping layer in the areas
adjacent to the trenches.
[0007] Therefore, there are significant needs for CMP compositions,
methods, and systems that can offer higher removal rate of silicon
oxide and high planarization efficiency, without forming the
dome-like topography. Slurries should also have excellent stopping
ability on silicon nitride or poly-Si films and provide low oxide
loss for wide trench structures.
BRIEF SUMMARY OF THE INVENTION
[0008] Described herein are oxide material CMP polishing
compositions, methods and systems that satisfy the need of
polishing semiconductor wafer comprising large sized silicon oxide
structures (with widths ranging from 0.1 mm to 50 mm) and trenches
with widths ranging from 0.01 mm to 10 mm with minimal rounding
(the formation of the dome-like topography) of the oxide features
while providing very high removal rates.
[0009] A polishing composition is provided comprising composite
particles comprising core particles with surfaces covered by
nanoparticles;
[0010] one or more additives selected from polymeric carboxylic
acids and salts thereof and one or more additives selected from
polymers containing alkoxylate groups;
[0011] a pH-adjusting agent selected from the group consisting of
sodium hydroxide, potassium hydroxide, cesium hydroxide, ammonium
hydroxide, quaternary organic ammonium hydroxide, and combinations
thereof; and DI water; wherein
[0012] the core particle is selected from the group consisting of
silica, alumina, titania, zirconia, polymer particle, and
combinations thereof; and the nanoparticle is selected from the
compounds of a group consisting of zirconium, titanium, iron,
manganese, zinc, cerium, yttrium, calcium, magnesium, fluorine,
lanthanum, strontium nanoparticle, and combinations thereof; and
the polishing composition has a pH of about 2 to about 12.
[0013] In one aspect of the invention the polishing composition the
core particle is silica particle, the nanoparticle is ceria
nanoparticle, wherein the silica is amorphous silica and the ceria
nanoparticles are singly crystalline. In another aspect, alone or
in combination with other aspects, the polishing composition of
comprises polymeric carboxylic acids and salts thereof selected
from the group consisting of polyacrylic acid, poly-methacrylic
acid, poly(methyl methacrylate) (PMMA), polyvinyl alcohol and
polystyrenesulfonic acid or salts thereof. In another aspect, alone
or in combination with other aspects, the polishing composition of
comprises polymers having alkoxylate groups are selected from the
group consisting of polyethylene glycol and polyethylene oxide. In
another aspect, alone or in combination with other aspects, the
polishing composition of comprises polymeric carboxylic acids and
salts thereof is ammonium polyacrylate and wherein said polyols
having hydroxyl groups is polyethylene glycol. In another aspect,
alone or in combination with other aspects, the polishing
composition has a pH ranging from 4 to 10. In another aspect, alone
or in combination with other aspects, the polishing composition of
comprises ceria coated silica composite particles, and ammonium
hydroxide; and having a pH ranging from 4 to 8.
[0014] In another aspect, alone or in combination with other
aspects, a method of the invention is provided for chemical
mechanical planarization of a semiconductor substrate comprising at
least one surface having at least one oxide layer and at least one
stopping layer beneath at least part of said at least one oxide
layer, and at least one trench within said substrate, said at least
one trench comprising a portion of said at least one oxide layer in
said trench, said at least one trench having a trench width of
greater than 0.01 mm, said at least one oxide layer comprises one
or more active oxide regions located on either side of said at
least one trench, said one or more active oxide regions having a
width greater than 0.1 mm, comprising the steps of: contacting the
at least one active oxide regions with a polishing pad; delivering
a polishing composition to the at least one surface, the polishing
composition comprising:
[0015] composite particles comprising core particles with surfaces
covered by nanoparticles; an additive selected from a compound
having a functional group selected from the group consisting of
organic carboxylic acids, amino acids, amidocarboxylic acids,
N-acylamino acids, and their salts thereof; organic sulfonic acids
and salts thereof; organic phosphonic acids and salts thereof;
polymeric carboxylic acids and salts thereof; polymeric sulfonic
acids and salts thereof; polymeric phosphonic acids and salts
thereof; arylamines, aminoalcohols, aliphatic amines, heterocyclic
amines, hydroxamic acids, substituted phenols, sulfonamides,
thiols, polyols having hydroxyl groups, polymers with alkoxylate
groups and combinations thereof; a pH-adjusting agent selected from
the group consisting of sodium hydroxide, potassium hydroxide,
cesium hydroxide, ammonium hydroxide, quaternary organic ammonium
hydroxide, and combinations thereof; and DI water; wherein
[0016] the core particle is selected from the group consisting of
silica, alumina, titania, zirconia, polymer particle, and
combinations thereof; and the nanoparticle is selected from the
compounds of a group consisting of zirconium, titanium, iron,
manganese, zinc, cerium, yttrium, calcium, magnesium, fluorine,
lanthanum, strontium nanoparticle, and combinations thereof; and
the polishing composition has a pH of about 2 to about 12;
[0017] and C) polishing the at least one active oxide region with
the polishing composition to expose said stopping layer.
[0018] In another aspect, alone or in combination with other
aspects, the polishing the nanoparticle is ceria nanoparticle, and
the composite particles are amorphous silica particles having
surfaces covered by singly crystalline ceria nanoparticles. In
another aspect, alone or in combination with other aspects, the
polishing method or system comprises a polishing composition having
a pH ranging from 4 to 10. In another aspect, alone or in
combination with other aspects, the polishing method or system
comprises a polishing composition further comprising one or more
additives selected from polymeric carboxylic acids and salts
thereof and one or more additives selected from the group
consisting of polyols having hydroxyl groups. In another aspect,
alone or in combination with other aspects, in the polishing method
or system, the polishing composition comprises ceria coated silica
composite particles, ammonium hydroxide; and has a pH ranging from
4 to 8. In another aspect, alone or in combination with other
aspects, in the polishing method or system, the polishing
composition comprises one or more additives selected from polymeric
carboxylic acids and salts thereof selected from the group
consisting of polyacrylic acid, poly-methacrylic acid, polyvinyl
alcohol and polystyrenesulfonic acid or salts thereof, and said one
or more additives selected from the group consisting of polymers
with alkoxylate groups selected from the group consisting of
polyethylene glycol and polyethylene oxide. In another aspect of
the method or method, alone or in combination with other aspects,
the at least one oxide layer is a silicon oxide layer and/or the
polishing removal rate for the at least one oxide layer is equal to
or greater than 5000 or 7000 or 9000 A/min. In another aspect,
alone or in combination with other aspects, in the polishing the at
least one trench has a trench width of 0.01 mm to 10 mm and at
least one of the one or more active oxide regions has a width
ranging from 0.1 mm to 50 mm. In another aspect, alone or in
combination with other aspects, in the polishing method or system,
the substrate has at least two trenches, and at least two active
oxide regions, each of said at least two trenches having a trench
width of 0.01 mm to 10 mm and each of said at least two active
oxide regions, having a width ranging from 0.1 mm to 50 mm and/or
the at least one of the one or more active oxide regions is greater
than 1 micron in height prior to said polishing step. In another
aspect, alone or in combination with other aspects, in the
polishing system and method or system, the structure is used for
3D-NAND. In another aspect, alone or in combination with other
aspects, the polishing composition, method or system comprises a
polishing composition has a pH ranging from 4 to 10 and the change
of size distribution of composite particles under a disintegrative
force is less than 5%. In another aspect, alone or in combination
with other aspects, the polishing composition, system or method
comprises the polishing composition further comprises one or more
additives selected from polymeric carboxylic acids and salts
thereof selected from the group consisting of polyacrylic acid,
poly-methacrylic acid, polyvinyl alcohol and polystyrenesulfonic
acid or salts thereof, and one or more additives selected from the
group consisting of polymers with alkoxylate groups selected from
the group consisting of polyethylene glycol and polyethylene
oxide.
[0019] Formulations of this invention are especially useful for
polishing semiconductor wafers for 3D-NAND application.
[0020] CMP polishing compositions described herein comprise ceria
coated silica particles and an additive for suppressing the removal
rate of the stopping film.
[0021] Ceria coated silica particles comprise silica particles as
the core particles covered with ceria nanoparticles forming a
shell. The silica base particles are amorphous; and the ceria
nanoparticles are singly crystalline.
[0022] The amount of nanoparticles covering the surface of the core
particles preferably falls within the following range in terms of
the solid weight ratio. The solid weight (b) of the nanoparticles
relative to the solid weight (a) of the core particles is
(b)/(a)=0.01 to 1.5, preferably 0.01 to 1.2.
[0023] Diameter of the ceria nanoparticles covering the core
particle is preferably greater than 10 nm, preferably more than 13
nm. Having larger ceria particle diameter would allow higher
removal rate to be possible.
[0024] Core particle size may range from 10 nm to 500 nm,
preferably between 20 nm to 200 nm, most preferably between 50 nm
and 150 nm.
[0025] Ceria coated silica particles are present in an amount from
0.01 wt % to 20 wt %, preferably, from 1 wt % to 10 wt %, more
preferably, from about 3 wt % to about 8 wt %.
[0026] Chemical additive for suppressing removal rates of the
stopping film may be a compound having a functional group selected
from the group consisting of organic carboxylic acids, amino acids,
amidocarboxylic acids, N-acylamino acids, and their salts thereof;
organic sulfonic acids and salts thereof; organic phosphonic acids
and salts thereof; polymeric carboxylic acids and salts thereof;
polymeric sulfonic acids and salts thereof; polymeric phosphonic
acids and salts thereof; arylamines, aminoalcohols, aliphatic
amines, heterocyclic amines, hydroxamic acids, substituted phenols,
sulfonamides, thiols, polyols having hydroxyl groups, polymers with
alkoxylate groups and combinations thereof. Preferred chemical
additives are polyacrylic acid or its derivatives; polyethylene
glycol; or mixtures of polyacrylic acid or its derivatives and
polyethylene glycol. Preferred molecular weight of polyacrylic acid
compound is between 1000 and 100,000, or between 5,000 and 50,000
or between 10,000 and 20,000. Polyethylene glycol molecular weight
can be between 1,000 and 20,000, or between 5,000 and 15,000.
[0027] The total amount of the one or more chemical additives range
from about 0.01 wt. % to 2 wt % relative to the total weight of the
CMP composition. The preferred range is from about 0.05 wt % to 1%
or from about 0.1 wt % ppm to 0.5 wt %.
[0028] CMP compositions may also optionally include other types of
additives such as one or more of the following: pH adjusting
agents, surfactants, dispersants and biological growth
inhibitors.
[0029] The pH-adjusting agent includes, but is not limited to,
sodium hydroxide, cesium hydroxide, potassium hydroxide, cesium
hydroxide, ammonium hydroxide, quaternary organic ammonium
hydroxide (e.g. tetramethylammonium hydroxide) and mixtures of any
of the above.
[0030] The amount of pH-adjusting agent ranges from about 0.0001 wt
% to about 5 wt % relative to the total weight of the CMP
composition. The preferred range is from about 0.0005% to about 1
wt %, or from about 0.0005wt % to about 0.5 wt %
[0031] The pH of the CMP composition ranges from about 2 to about
12. The preferred range is about 3 to about 10, or from about 4 to
7.5.
[0032] The CMP composition also comprises DI water. The DI water is
present between from 60 wt % to 99 wt %, or 70 wt % to 98 wt % or
80 wt % to 95 wt %. In some embodiments, the DI water (if an amount
is not specified) may be the balance (or remainder) of the CMP
slurry composition.
[0033] CMP slurry compositions of this invention, polish the oxide
films at high rates and stopping films at low rates, thereby
providing high throughput and ability to stop on the stopping
films. In some embodiments, the CMP compositions of this invention
are used to polish oxide layers thicker than 1 micron and stop on
the second film (the stopping film) such as nitride or poly-Si. One
such application of these polishing is in 3D-NAND memory
fabrication. A typical structure would include at least one trench
with at least one trench having a width from 0.1 mm to 10 mm, at
least one active oxide regions with at least one active oxide
region having a width from 1 micron to 50 mm. More typically, the
structures would comprise at least two trenches with at least two
trenches having widths from 0.1 mm to 10 mm. Additionally or
alternatively, more typically the structure would comprise at least
two active oxide regions with at least two active oxide regions
having widths from 1 micron to 50 mm. CMP compositions described
herein, can polish the active oxide regions at very high rates
while minimizing formation of rounded topographic features
resembling domes. Oxide removal rates are preferably greater than
5000 .ANG./min, or more preferably more than 7000 .ANG./min or most
preferable greater than 9000 .ANG./min. It is desired that the
maximum height of the rounding (maximum height of the dome
features) when the stopping film starts to clear (to be exposed)
from (beneath the) active oxide regions, is less than 1500 .ANG.,
or less than 1000 .ANG.or less than 500 .ANG.. These heights were
measured for a 10 micron wide oxide regions separated by 3 micron
trenches. For smaller (active) oxide regions, even smaller rounding
heights can be achieved using the method and CMP slurry of this
invention. For illustration purposes, FIG. 3 shows a structure that
has 600 A of maximum rounding height as measured by a profilometer.
The top dashed line on FIG. 3 indicates the maximum height of the
active oxide and the lower dashed line indicates the edge of the
trench where the rounding begins. The difference between those two
measurements is the maximum height of rounding.
BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS
[0034] FIG. 1(a) shows the schematic cross-section of an exemplary
structure prior to polishing. FIG. 1(b) shows dome structures that
may result from polishing the structure shown in FIG. 1(a) when
using a CMP slurry that is not of this invention. FIG. 1(c) shows
the desired topography of the structure after polishing with a CMP
slurry.
[0035] FIG. 2(a) shows a schematic of a cross-section of a portion
of a substrate to be polished using the CMP slurry and the method
of this invention.
[0036] FIG. 2(b) shows a schematic of the pattern lay-out (the top
surface) of a portion of a substrate (patterned wafers) polished in
the examples described herein.
[0037] FIG. 3 shows a typical profilometer scan showing how the
rounding of patterned structures is measured.
DETAILED DESCRIPTION OF THE INVENTION
[0038] Described herein are oxide material CMP polishing
compositions, methods and systems that satisfy the need of
polishing semiconductor wafer comprising large sized silicon oxide
structures (with widths ranging from 0.1 mm to 50 mm) and trenches
with widths ranging from 0.01 mm to 10 mm with minimal rounding
(the formation of the dome-like topography) of the oxide features
while providing very high removal rates. Formulations of this
invention are especially useful for polishing semiconductor wafers
for 3D-NAND application.
[0039] Each of the composite abrasive particles has a core particle
and many nanoparticles covering the surface of the core particle.
The core particle is selected from the group consisting of silica,
alumina, titania, zirconia, and polymer particle. The nanoparticles
are selected from the group consisting of oxides of zirconium,
titanium, iron, manganese, zinc, cerium, yttrium, calcium,
magnesium, fluorine, lanthanum and strontium nanoparticles.
[0040] The amount of nanoparticles covering the surface of the core
particles preferably falls within the following range in terms of
the solid weight ratio. The solid weight (b) of the nanoparticles
relative to the solid weight (a) of the core particles is
(b)/(a)=0.01 to 1.5, preferably 0.01 to 1.2.
[0041] One of the examples of the composite particles is to have
silica as the core particles and ceria as the nanoparticles; and
each silica core particle has ceria nanoparticles covering its
shell. The surface of each silica particle is covered by ceria
nanoparticles. The silica base particles are amorphous; and the
ceria nanoparticles are singly crystalline.
[0042] Diameter of the ceria nanoparticles covering the core
particle is preferably greater than 10 nm, preferably more than 13
nm. Having larger ceria particle diameter would allow higher
removal rate to be possible.
[0043] Core particle size may range from 10 nm to 500 nm,
preferably between 20 nm to 200 nm, most preferably between 50 nm
and 150 nm.
[0044] Another aspect of the present invention, involves using
ceria coated silica particles that do not disintegrate under
polishing forces. It is hypothesized that if the particles do not
breakdown under the action of polishing forces (i.e. disintegrative
forces) and keep the characteristic of original particle size, then
the removal rate would remain high. If the particles on the other
hand disintegrate under polishing forces, the removal rate would
decrease owing to effectively smaller abrasive particle size.
Breaking of the particles may also yield irregular shaped particles
which may have undesirable effect on scratching defects. Particle
stability under disintegrative forces can also be determined by
subjecting the formulation to the ultrasonication treatment for
half an hour and measuring the changes in size distribution.
Preferred conditions for ultrasonication treatment are 1/2 hour
immersion in bath with 42 KHZ frequency at 100 W output. Particle
size distribution can be measured by using any suitable technique
such as Disc Centrifuge (DC) method or Dynamic Light Scattering
(DLS). Changes in size distribution can be characterized in terms
of changes in mean particle size or D50 (50% particles below this
size) or D99 (99% particles below this size) or any similar
parameters. Preferably the changes in particle size distribution of
ceria coated silica particles after ultrasonication treatment is
less than 10%, more preferably less than 5% or most preferably less
than 2%; by using for example DC and mean particle size, D50, D75
and/or D99. Using such stable particles in CMP slurry formulations
would allow more effective utilization of polishing forces for film
material removal and would also prevent generation of any irregular
shapes that would contribute to scratching defects.
[0045] In another aspect of the present invention, the silica-based
composite particle having an amorphous oxide layer including at
least one type of element among aluminum, zirconium, titanium,
iron, manganese, zinc, cerium, yttrium, calcium, magnesium,
fluorine, lanthanum silicon, and strontium on the surface of an
amorphous silica particle .ANG., and a crystalline oxide layer B
including at least one type of element selected from among
zirconium, titanium, iron, manganese, zinc, cerium, yttrium,
calcium, magnesium, fluorine, lanthanum and strontium
thereupon.
[0046] Since advanced CMP applications require extremely low levels
metals such as sodium on the dielectric surface after polishing, it
is desired to have very low trace metals, especially sodium in the
slurry formulations. In certain preferred embodiments the
formulations comprise ceria coated silica particles that have less
than 5 ppm, more preferably less than 1 ppm most preferably less
than 0.5 ppm of sodium impurity levels for each percent of
particles in the formulations by weight. The composite particles
are used as abrasive in the CMP compositions, formulations or
slurries ("CMP composition", "CMP formulation", or CMP slurry" are
used interchangeably). Note the terms, "film" and "layer" are used
interchangeably herein. Any weight percentages (wt %) unless
otherwise indicated are based on the total weight of the CMP
formulation at the point of use. The height of a layer is measured
from the top surface of a layer to the bottom of the layer
interfacing with the underlying second layer. Height can be
measured by taking a cross-section of the structure or by a
suitable elliposometric technique. For example, the height h of the
active oxide region is shown in FIG. 1(a). The width of a layer of
a material on the top surface of a structure can be determined by
visually inspecting and measuring the material on the top surface.
Alternatively, the width can also be determined from a
cross-section. The width w of a trench is shown in FIG. 2(b). The
width of the structures shown in FIG. 2(b) are written on the
structures in the figure. Note the term width will be used to mean
both or either of the length and width of a region. So for example,
the width of the stopping layer and the active oxide region thereon
(shown as the white rectangle) in the bottom right corner of FIG.
2(b) is 10.0 mm or 8.0 mm. When following the Scan A arrow, the
measured width of that same stopping layer and the active oxide
region thereon is 10.0 mm. Note that oxide will also be present
above the trench as shown in FIG. 1(a) and it should and will be
removed with the active oxide regions located adjacent to the
trench as shown in FIG. 1(a) to achieve the result shown in FIG.
1(c); however, the oxide located directly above the trench is not
included in the "active oxide region" when the widths of the active
oxide region are described herein. Oxide films are silicon oxide
films only.
[0047] The CMP composition comprises composite particles, a pH
adjusting agent that is used to adjust pH of the CMP composition to
the optimized pH condition; a suitable chemical additive to
enhance/suppress the removal rate of polish stop layer/film;
optional additives; and the remaining being water.
[0048] Ceria coated silica particles are present in an amount from
0.01 wt % to 20 wt %, from 1 wt % to 10 wt %, or from about 3 wt %
to about 8 wt %.
[0049] Chemical additive includes, but is not limited to a compound
having a functional group selected from the group consisting of
organic carboxylic acids, amino acids, amidocarboxylic acids,
N-acylamino acids, and their salts thereof; organic sulfonic acids
and salts thereof; organic phosphonic acids and salts thereof;
polymeric carboxylic acids and salts thereof; polymeric sulfonic
acids and salts thereof; polymeric phosphonic acids and salts
thereof; arylamines, aminoalcohols, aliphatic amines, heterocyclic
amines, hydroxamic acids, substituted phenols, sulfonamides,
thiols, polyols having hydroxyl groups, polymers comprising
alkoxylate groups, and combinations thereof. Preferred chemical
additives are polymeric carboxylic acids or salts thereof and
polymers with alkoxylate groups. Polymeric carboxylic acids include
but not limited to polyacrylic acid, poly-methacrylic acid,
polyvinyl alcohol and polystyrenesulfonic acid. Polymeric
carboxylic acids may include copolymers where one or more monomers
could be carboxylic acids or its derivatives. Additives may also
include salts of polymeric carboxylic acids, these may include but
not limited to ammonium salts, potassium salts, cesium salts,
various salts with quaternary ammonium hydroxide bases and salts
with amine bases. It may be preferred for certain applications that
the salt may not contain metals. Preferred polymeric carboxylic
acid compound is ammonium polyacylate. Preferred molecular weight
of polyacrylic acid compound is between 1000 and 100,000, or
between 5,000 and 50,000 or between 10,000 and 20,000. Polymers
comprising alkoxylate groups may include polymers and copolymers
containing ethylene oxide repeating units, includes polyoxyethylene
(POE), polypropylene glycol(PPG), and copolymer of POE and PPG.
[0050] An example is polyoxyethylene (POE), having the general
molecular structure of
##STR00001##
wherein n refers to the total numbers of the repeating unit ranging
from 4 to 125000; and the molecular weights (grams/mole) ranging
from 200 to 5,000,000. A preferred range is from 1000 to 1000000;
and the most preferred concentration range is from 10000 to
400000.
[0051] Polyoxyethylene (POE), is also called polyethylene oxide
(PEO), or polyethylene glycol(PEG).The three names are chemically
synonymous, but historically PEG has tended to refer to oligomers
and polymers with a molecular mass below 20,000 g/mol, PEO to
polymers with a molecular mass above 20,000 g/mol, and POE to a
polymer of any molecular mass.
[0052] The ethoxylated surfactants are compounds that contain
hydrophobic part as for example a hydrocarbon or polypropylene
oxide chain as well as hydrophilic part which is the polyethylene
oxide chain.
[0053] The suitable ethoxylated surfactants include, but are not
limited to ethoxylated non-ionic surfactant, such as alkyl phenol
ethoxylate, fatty alcohol ethoxylate, fatty amine ethoxylate and
propylene oxide ethylene oxide block copolymers.
[0054] Preferred polymer with alkoxylate groups is polyethylene
glycol. Its molecular weight can range from 1,000 to 20,000, and
more preferably between 5,000 and 15,000.
[0055] The amount of (chemical) additive ranges from about 0.01 wt
% to 2 wt % relative to the total weight of the CMP composition.
The preferred range is from about 0.05 wt % to 1% or from about 0.1
wt % ppm to 0.5 wt %.
[0056] CMP compositions may also optionally include one or more of
other types of additives such as pH adjusting agents, surfactants,
dispersants or biological growth inhibitors and mixtures of any of
the above.
[0057] The pH-adjusting agent includes, but is not limited to,
sodium hydroxide, cesium hydroxide, potassium hydroxide, cesium
hydroxide, ammonium hydroxide, quaternary organic ammonium
hydroxide (e.g. tetramethylammonium hydroxide) and mixtures
thereof.
[0058] The amount of pH-adjusting agent ranges from about 0.0001 wt
% to about 5 wt % relative to the total weight of the CMP
composition. The preferred range is from about 0.0005% to about 1
wt %, or from about 0.0005 wt % to about 0.5 wt %.
[0059] The pH of the CMP composition ranges from about 2 to about
12. The preferred range is about 3 to about 10 or from about 4 to
7.5.
[0060] The CMP composition may comprise a surfactant or a mixture
of surfactants. Surfactants may be anionic, cationic, nonionic or
zwitterionic in nature. While there are many suitable surfactant
additives for the slurry, preferred surfactant additives include
dodecyl sulfate sodium salt, sodium lauryl sulfate, dodecyl sulfate
ammonium salt, alcohol ethoxylates, acetylenic surfactant,
polyethyleneimine, ethoxylated fatty amine and
stearylbenzyldimethylammonium chloride or nitrate and any
combination thereof. Suitable commercially available surfactants
include TRITON DF 16.TM. manufactured by Dow Chemicals and various
surfactants in SUIRFYNOL.TM., DYNOL.TM., Zetasperse.TM.,
Nonidet.TM., and Tornado.TM. surfactant families, manufactured by
Air Products and Chemicals.
[0061] Various anionic, cationic, nonionic and zwitterionic
surfactants having molecular weight in the range from less than
1000 to greater than 30,000 are contemplated as dispersants.
Included are sodium, potassium, or preferably ammonia salts of
stearate, lauryl sulfate, alkyl polyphosphate, dodecyl benzene
sulfonate, di-isopropylnaphthalene sulfonate,
dioctylsulfosuccinate, ethoxylated and sulfated lauryl alcohol, and
ethoxylated and sulfated alkyl phenol.
[0062] Various cationic surfactants include polyethyleneimine,
ethoxylated fatty amine and stearylbenzyldimethylammonium chloride
or nitrate.
[0063] Addition of a surfactant may be useful to reduce the
within-wafer-non-uniformity (WIWNU) of the wafers, thereby
improving the surface of the wafer and reducing wafer defects.
[0064] The CMP composition may comprise a dispersing additive to
stabilize particle dispersion.
[0065] The amount of surfactant ranges from about 0.0001 wt % to
about 10 wt % relative to the total weight of the CMP composition.
The preferred range is from about 0.001 wt % to about 1 wt %, or
from about 0.005 wt % to about 0.1 wt %.
[0066] The suitable dispersing additive includes, but is not
limited to organic acids and their salts; polymeric acids and their
salts; water soluble copolymers and their salts; copolymers and
their salts containing at least two different types of acid groups,
such as carboxylic acid groups, sulfonic acid groups, or phosphonic
acid groups in the same molecule of a copolymer, polyvinyl acid and
salt thereof, polyethylene oxide, polypropylene oxide, and
combinations thereof. Some examples of dispersants include:
polyethylene glycols; lecithin; polyvinyl pyrrolidone;
polyoxyethylene; isoctylphenyl ether; polyoxyethylene nonylphenyl
ether; amine salts of alkylaryl sulfonates; polyacrylic acid,
polymethacrylic acid and their salts.
[0067] The amount of dispersant ranges from about 0.0001 wt % to
about 10 wt % relative to the total weight of the CMP composition.
The preferred range is from about 0.001 wt % to about 1 wt % or
from about 0.005 wt % to about 0.1 wt %.
[0068] Formulations may also comprise water soluble polymers which
may comprise anionic or cationic or non-ionic or combinations of
groups.
[0069] The CMP composition may comprise biological growth
inhibitors or preservatives to prevent bacterial and fungal growth
during storage.
[0070] The biological growth inhibitors include, but are not
limited to, tetramethylammonium chloride, tetraethylammonium
chloride, tetrapropylammonium chloride, alkylbenzyldimethylammonium
chloride, and alkylbenzyldimethylammonium hydroxide, wherein the
alkyl chain ranges from 1 to about 20 carbon atoms, sodium
chlorite, and sodium hypochlorite.
[0071] Some of the commercially available preservatives include
KATHON.TM. and NEOLENE.TM. product families from Dow Chemicals, and
Preventol.TM. family from Lanxess. More are disclosed in U.S. Pat.
No. 5,230,833 (Romberger et al.) and US Patent Application No. US
20020025762. The contents of which are hereby incorporated by
reference as if set forth in their entireties.
[0072] CMP formulations may be made in concentrated form and
diluted at point of use by adding water. Alternatively formulations
can be mixed at point of use by combining two or more components in
order to avoid issues such as poor shelf life stability owing due
to interactions between components.
[0073] The composite particles are used as abrasive in the CMP
compositions, formulations or slurries ("CMP composition", "CMP
formulation", or CMP slurry" are used interchangeably). The
formulations comprising ceria coated silica composite particles can
provide very high removal rates of silicon oxide films. Silicon
oxide films may be generally referred to as oxide films in the
description. Silicon oxide films could include a variety of films
and materials including but not limited to thermal oxide, films
deposited using Tetra Ethyl Ortho Silicate (TEOS) precursors, High
Density Plasma (HDP) oxide, High Aspect Ratio Process (HARP) films,
fluorinated oxide films, doped oxide films, Spin-On Glass (SOG),
flowable Chemical Vapor Deposited (CVD) films, optical glass,
display glass. These formulations can be used in stop-in-film
applications, where the polishing is stopped once the topography is
removed and a flat surface is achieved. Alternatively these
formulations can be used in applications that involve polishing the
bulk film and stopping at a stopping layer. Stopping layer may
comprise a silicon nitride or poly-Si film. Silicon nitride film
may be represented by a general formula Si.sub.xN.sub.y, where the
ratio x/y may range from 0.1 to 10. The silicon nitride may also
incorporate other elements such as but not limited to oxygen,
carbon, nitrogen. Poly-Si films may also contain various doping
additives.
[0074] CMP slurry compositions of this invention, polish the oxide
films at high rates and stopping films at low rates, thereby
providing high throughput and ability to stop on the stopping
films. In some embodiments, the CMP compositions of this invention
are used to polish oxide layers thicker than 1 micron and stop on
the second (stopping) film such as nitride or poly-Si. One such
application of these polishing is in 3D-NAND memory fabrication.
FIG. 1(a) shows the schematic cross-section of the typical
structure after the deposition of the active oxide layer onto a
structure comprising a trench in an underlying layer, with a
stopping layer located between the underlying layer and the active
oxide layer. (The stopping layer is not located in the trench.) The
trench structures are typically very wide (for example, more than
10 times or more than 100 times wider) as compared to other
structures and processes, such as shallow trench isolation, that
are used in semiconductor fabrication. A typical structure polished
in the method of this invention would include trenches with widths
that could range from 0.1 mm to 10 mm, or 0.5 mm to 10 mm, or 1 mm
to 10 mm, and active oxide regions with widths that can extend from
1 micron to 50 mm, or 5 microns to 50 mm, or 10 microns to 50 mm.
During polishing of wide structures, topographic features
resembling domes are often formed. This dome or rounded shaped
topography is associated with oxide residuals in the active region
and substantial loss of oxides in the trench regions. FIG. 1b is a
schematic showing dome shaped structures typically formed during
polishing such wide structures. An extensive over-polish would be
required in such cases to remove residual oxides from active
regions which would lead to severe loss of oxide(s) from the
trench, loss of the nitride stopping layer, as well as, damage to
the underlying layers. FIG. 1(c) shows the desired topography after
the CMP polishing step.
[0075] It is desired that the rounding (height of the dome
features) when the stopping film starts to clear from the active
oxide regions, is less than 1500 .ANG., or more preferably less
than 1000 .ANG. and most preferably less than 500 .ANG.. These
heights were measured for a 10 micron wide oxide regions separated
by 3 micron trenches. For smaller (active) oxide regions, even
smaller rounding heights can be achieved using the method and CMP
slurry of this invention. CMP removal rates can be measured either
based on thickness removed per unit time on blanket wafers or by
thickness removed per unit time on a patterned wafer. In certain
cases, patterned oxide rates may be substantially higher than the
blanket oxide rates. Similarly, there may be discrepancies in the
removal rates of stopping films in blanket vs. patterned
structures. The mechanism of differences in blanket and patterned
removal rates is not entirely known, but it may be dependent on how
the additives interact with the film surfaces at the localized
pressures on the patterned structures (wafers). In CMP
manufacturing environment where throughput of patterned wafer CMP
processing is a concern, high patterned oxide removal rates are
acceptable even if the blanket oxide removal rates are low. In
preferred embodiments, the silicon oxide films are polished at a
rate greater than 5000 .ANG./min, or more preferably more than 7000
.ANG./min or most preferable greater than 9000 .ANG./min. Removal
rate selectivity between the silicon oxide and the stopping film is
preferably greater than 10, or greater than 30.
Working Examples
[0076] Polishing Pad IC1010 pad, supplied by Dow Corporation;
[0077] TEOS oxide films by Chemical Vapor Deposition (CVD) using
tetraethylorthosilicate as the precursor
[0078] HDP oxide films made by high density plasma (HDP)
technique
[0079] SiN films- Silicon nitride films
[0080] PARAMETERS:
[0081] .ANG.: angstrom(s)--a unit of length
[0082] BP: back pressure, in psi units
[0083] CMP: chemical mechanical planarization=chemical mechanical
polishing
[0084] CS: carrier speed
[0085] DF: Down force: pressure applied during CMP, units psi
[0086] min: minute(s)
[0087] ml: milliliter(s)
[0088] mV: millivolt(s)
[0089] psi: pounds per square inch
[0090] PS: platen rotational speed or table-speed of polishing
tool, in rpm (revolution(s) per minute)
[0091] SF: polishing composition flow, ml/min
[0092] Removal Rates and Selectivity
[0093] Removal Rate (RR)=(film thickness before polishing--film
thickness after polishing)/polish time.
[0094] TEOS RR Measured TEOS removal rate at 4.7 psi down pressure
and 87 RPM table-speed of the CMP tool
[0095] HDP RR Measured HDP removal rate at 4.7 psi down pressure
and 87 RPM table-speed of the CMP tool
[0096] SiN RR Measured SiN removal rate at 4.7 psi down pressure
and 87 RPM table-speed of the CMP tool
[0097] Selectivity of TEOS/SiN=TEOS RR/SiN RR; HDP/SiN=HDP RR/SiN
RR at same down force and table-speed (psi)
[0098] All percentages are weight percentages unless otherwise
indicated.
[0099] General Experimental Procedure
[0100] In the examples presented below, CMP experiments were run
using the procedures and experimental conditions given below.
[0101] The CMP tool that was used in the examples is a Mirra.RTM.,
manufactured by Applied Materials, 3050 Boweres Avenue, Santa
Clara, Calif., 95054. IC1010 pads from Dow Chemicals were used for
polishing.
[0102] The oxide film thickness specifications are summarized
below:
[0103] TEOS: 15,000 .ANG.
[0104] HDP: 10,000 .ANG.
[0105] 3D NAND Integration test wafers used in the examples below
were purchased from Silyb Wafer Services. FIGS. 2(a) and 2(b) show
schematics of the cross-section and the pattern lay-out of wafers
respectively. The trench height was 20,000 .ANG.. A 30,000 TEOS
layer was deposited over the wafer to fill in the trench. SiN layer
thickness was 500 .ANG..
[0106] The pattern wafers were scanned using P17 profilometer
(Manufactured by KLA Tencor) to measure the topography. The scans
were performed along 10 micron.times.10 micron and 10
micron.times.8 micron structures as marked by Scan A in the pattern
layout shown in FIG. 2. FIG. 3 shows a typical profilometer scan
showing how the rounding is measured.
[0107] Oxide thickness measurements on patterned structures were
performed using Therma-Wave Opti-Probe 3290 DUV tool. The
measurements were performed along scan A line shown in FIG. 2(b).
The average thickness of oxide in the trench was calculated based
on the measurements of 29 points in the 3 mm trench. Oxide loss in
the trenches is calculated by subtracting average oxide thickness
in the trenches after polishing from the trench height (2 microns).
The average thickness of oxide in the active region was calculated
based on the measurements of 99 points along the 10 mm scan in the
active oxide region. Patterned wafer active TEOS oxide removal rate
was calculated based on change in oxide thickness in the active
regions after 60 second polish.
[0108] Pattern clear time was determined as the time at which the
nitride layer is first exposed.
[0109] Ceria coated silica particles (CPOP-20) used in the examples
were procured from JGC C&C Ltd (Kawasaki City, Japan). CPOP-20
particles are made by the methods described in JP20131191131,
JP2013133255, JP2015-169967, and JP2015-183942. Mean particle size
of these particles measured by Disc Centrifuge analysis method
(DC24000 UHR from CPS Instruments) was 97.7 Comparative abrasive
particles included calcined ceria particles (Mean Particle Size: 99
nm) and colloidal ceria particles with mean particle size 110 nm
(HC-60 ceria particles from Solvay, Rhodia Inc, 8 Cedar Brook Dr.,
Canbury, N.J.)
Example 1
[0110] The CMP compositions comprised abrasive particles, 0.12 wt %
ammonium polyacrylate (Molecular Weight 16000-18000), ammonium
hydroxide, and water. The CMP compositions had a pH of 5. Three
different abrasive particle types were used; calcined ceria,
colloidal ceria and ceria coated silica particles. The particle
concentrations was varied from 1 wt % to 5 wt %. Polishing was
performed on IC1000 pad with 87 RPM table speed and 4.7 psi
membrane pressure with 200 ml/min slurry flow rate.
[0111] These formulations were used to polish TEOS (oxide films
deposited using Chemical Vapor Deposition technique with tetraethyl
orthosilicate precursor), HDP
[0112] (Oxide film deposited with High Density Plasma technique)
and SiN blanket films. Table 1 provides the removal rates and
polish selectivity data for these films.
TABLE-US-00001 TABLE 1 % Removal Rate Removal Rate Selectivity
Abrasive (.ANG./min) TEOS/Nitride HDP/Nitride Particles TEOS HDP
SiN Selectivity Selectivity Calcined 1% 3336 2905 171 20 17 Ceria
3% 5784 4411 209 28 21 5% 6347 5857 228 28 26 Colloidal 1% 2508
2031 191 13 11 Ceria 3% 2693 3493 219 12 16 (HC60) 5% 5151 4404 232
22 19 Ceria 1% 4016 5540 204 20 27 Coated 3% 9547 9116 244 39 37
Silica 5% 11904 11825 272 44 43 Particles
[0113] It is evident that for the CMP slurries comprising calcined
and colloidal ceria, achieving removal rates of more than 10,000
.ANG./min, that is required for several oxide polishing
applications, would require very high concentrations of abrasive
particles. Slurries with very high concentrations of ceria based
particles, such as greater than 7 wt % are considered unpractical
for commercial applications because of cost and high defectivity
associated with high concentration of ceria particles. Ceria coated
silica particles not only provide high removal rates of oxide
films, but they also offer a high oxide to nitride removal rate
selectivity, which is beneficial for polishing 3D-NAND
structures.
Example 2
[0114] CMP compositions were made comprising 5 wt % ceria coated
silica particles, 0.12 wt % ammonium polyacrylate (Molecular Weight
16000-18000), ammonium hydroxide, and water being balance. The pH
was adjusted to different values using ammonium hydroxide. Table 2
provides the removal rates on TEOS, HDP and SiN films along with
removal rate selectivity between the films with these
formulations.
[0115] Increasing the pH to and/or above 7 seems to increase the
SiN rates and thus reduce the oxide/nitride selectivity. pH lower
than 7 is more suitable to achieve high oxide rates and providing a
stop on nitride films.
TABLE-US-00002 TABLE 2 Removal Rate Selectivity Removal Rate
(.ANG./min) TEOS/Nitride HDP/Nitride pH TEOS HDP SiN Selectivity
Selectivity 5 11904 11825 272 44 43 6 13595 11924 296 46 40 7 13299
11935 1303 10 9 8 12656 12141 1389 9 9
Example 3
[0116] 3D NAND test wafers were polished using an IC1010 pad at 3
psi down-force and 126 RPM table speed with 200 ml/min slurry flow.
The slurry formulations comprised 5 wt % abrasive particles, 0.12
wt % ammonium polyacrylate (Molecular weight 16,000-18,000) and DI
water. Two types of abrasive particles were compared, calcined
ceria and ceria coated silica particles.
[0117] Table 3 summarizes the patterned wafer data. It was
determined that during 60 second polish, the amount of active oxide
regions removed using the CMP slurry formulation with calcined
ceria was 4976 .ANG., whereas the formulation with ceria coated
silica particles removed 13515 .ANG. of active oxide regions. The
results are consistent with the blanket oxide results. Surface
profilometry showed using formulations with ceria coated silica
particles, there is very little rounding (297 .ANG.). Formulations
made with conventional calcined provide unacceptably high rounding
(4396 .ANG.).
TABLE-US-00003 TABLE 3 Effect of abrasive type on rounding Active
Oxide removal in 60 Abrasive second polish (.ANG.) Rounding at
Clear Calcined ceria 4976 4396 Ceria Coated Silica 13515 297
Example 4
[0118] CMP compositions comprised: 5 wt % of ceria coated silica as
the abrasive, different additives (ammonium polyacrylate (Molecular
Weight 16000-18000) and polyethylene glycol (PEG) (Molecular weight
8000), and ammonium hydroxide to adjust the pH to 5. 3D-NAND test
wafers and blanket TEOS wafers were polished with the same process
conditions described in Example 3. Table 4 summarizes the polish
test data.
TABLE-US-00004 TABLE 4 Effect of additives on rounding and oxide
loss in trenches Patterned Blanket TEOS Oxide Trench Removal
Removal Oxide Loss Rounding Additive Rate (.ANG./min) Rate
(.ANG./min) (.ANG.) at Clear (.ANG.)@ clear 0.12% Ammonium
Polyacrylate 7923 13515 3532 297 0.3% Ammonium Polyacrylate 2041
11334 1730 586 0.375% Ammonium 1831 10314 1501 484 Polyacrylate
0.12% Ammonium 5101 11680 1701 758 Polyacrylate + 0.077% PEG 0.12%
PEG 7000 10351 1341 250
[0119] The results show that by increasing the ammonium
polyacrylate concentrations, trench oxide loss is substantially
reduced. While increase in ammonium polyacrylate concentration
reduces blanket removal rates, there is no significant effect on
patterned oxide removal rates. Polyethylene glycol by itself or in
combination with ammonium polyacrylate is able to substantially
able to reduce trench oxide loss while having high blanket and
patterned oxide removal rates. Rounding with both types of
additives is very low. Dispersions of particles in water were
tested for the stability under a disintegrative force that is under
ultrasonic disintegration.
Example 5
[0120] Dispersions of particles in water were tested for the
stability under a disintegrative force, that is, under ultrasonic
disintegration.
[0121] The experiment was performed in Branson 2510R-MI Sonic bath
with a 100 watt output at 42 KHz. Ceria coated silica CPOP-20
particles as described in example 1 were compared against CP2
particles that were prepared as per the method described in US
2012/0077419 for comparison. Mean Particle Size (MPS) measured by
Disc Centrifuge Analysis was 41 nm.
TABLE-US-00005 TABLE 3 MPS d50 d75 d99 sample (nm, DC) (nm, DC)
(nm, DC) (nm, DC) CPOP-20 97.7 94.7 114.8 172.0 CPOP-20 sonicated
30 min 96.7 94.1 114.3 171.1 Change % 1.0% 0.6% 0.4% 0.5% CP2 41.1
35.7 45.0 136.4 CP2 sonicated 30 min 33.6 30.4 36.7 77.0 Change %
18.2% 14.8% 18.4% 43.5%
[0122] The particle size distribution as measured by Disc
Centrifuge method (DC24000 UHR from CPS Instruments) before and
after ultrasonication treatments for CPOP-20 and CP2 particles were
shown in Table 3 respectively.
[0123] The results indicated that the particles used in
formulations of this invention did not show change in size
distribution, indicating a strong bonding between core and the
coated particles.
[0124] The change in size distribution of CP2 particles was
>14%. Data in Table 3 also showed that the particle size
distribution shifting towards smaller particles, indicating that
composite particles may not be stable, such as the weak bonding
between core and the coated particles.
[0125] The foregoing examples and description of the embodiments
should be taken as illustrating, rather than as limiting the
present invention as defined by the claims. As will be readily
appreciated, numerous variations and combinations of the features
set forth above can be utilized without departing from the present
invention as set forth in the claims. Such variations are intended
to be included within the scope of the following claims.
* * * * *